When a colleague showed me Star Chart, I was struck by the gorgeous graphics of this astronomy app. I downloaded it and have put Star Chart (for iPad) through its paces. It's a fine addition to the planetarium app cosmos, all the more so because it's free, but some of the in-app purchases you're offered to expand its capabilities may not be worth their price.

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Star Chart Basics
Star Chart (not to be confused with Wil Tirion's Star Charts app) works with the iPad, iPhone (it's optimized for iPhone 5), and iPod touch; I tested it with an iPad 2. Like other planetarium apps, Star Chart displays a depiction of the night sky as it appears in the direction you're holding the iPad; the star patterns change as you pan the tablet or skew it upward. You can pinch the screen for a wider-field view, or stretch it to zoom. During the daytime, it still shows the stars, as well as the Sun (and a funky, prismatic lens-flare effect when you're pointing near the Sun.) It defaults to your location, but you can also set it to show the sky for various major cities around the world.

In the upper right corner, the time is displayed. Tapping it shows the year, month, day, hour, and minute, and by moving a vertical slider at the screen's right edge, you can change the time and date to show the sky for any date and time between the years 4713 BC and 10,000 AD.

At the screen's lower right corner are Search and Settings icons. Settings lets you change the display appearance, how constellations and other elements are depicted, your location, and more. Search lets you find stars (by name), planets, constellations, and Messier objects (galaxies, star clusters, and nebulae); tapping on the name will take you to the object, and launch a sidebar with basic data about it. A calendar lets you view notable celestial events for different dates, but many (meteor showers, or a comet's closest approach to the Sun) are only seen with the purchase of certain paid add-ons.

Your Virtual Spaceship
One fun feature in Star Chart is the planetary tours it offers. When you tap any planet on screen, a sidebar with data and descriptive information pops up. At the top is a video link with the image of a planettapping on it takes you on a brief virtual flyby of the planet.

Stretching the image of the planet eventually shows it as a disk with its unique character, rather than just a point of light. It also reveals the planet's major moons. It shows 6 of Saturn's moons, and Jupiter's 4 large Galilean satellites. To get a more complete complement of moons, as well as to display dwarf planets (in addition to Pluto, which comes gratis), you can buy the Extended Solar System add-on ($1.99).

Get Your 17 Comets for $1.99
Star Chart comes with no comets; I downloaded the Comets add-on as an in-app purchase for $1.99. One currently prominent comet that it displays is Comet ISON, which in a few days from this writing will make an exceptionally close passage to the Sun. It provides some basic descriptive information and data about the comet, whose size and appearance in the app are relatively true to life, unlike in the Editors' Choice SkySafari 3 (for iPad) , where ISON is shown with a much longer tail than in reality.

However, ISON is one of but 17 comets included in the add-on. The others are all short-period comets, which circle the Sun in less than 200 years. Some are notable objects, such as Comets Halley, Swift-Tuttle (the parent body of the Perseid meteor shower), and Tempel-Tuttle (the parent body of the Leonid meteor shower), but they won't actually be observable for decades. The basic ($2.99) version of SkySafari includes well over 200 comets, both short- and long-period objects, including Comet Lovejoy (C/2013 R1), which as of this writing is visible to the unaided eye. Lovejoy is absent from Star Chart. Hopefully Star Chart's makers will expand the selection of comets.

While we're on the subject of in-app purchases, other add-ons include Satellites ($2.99) which lets you track the International Space Station and other artificial satellites; Meteor Showers ($2.99) which includes the date and the location of the radiant (the point in the sky where the meteors seem to emanate) for major meteor showers; Enhanced Constellations ($4.99), an upgrade to show high-resolution versions of the mythical figures and other constellation figures that are shown in low resolution in the free version, and Enhanced Messier Catalog ($4.99), with detailed depictions of the deep-sky objects (galaxies, nebulae, and star cluster) that comprise comet hunter Charles Messier's catalog of objects that could be mistaken for comets.

Hey, It's Free
Star Chart (for iPad) offers a lot for a free planetarium app: an attractive depiction of the sky; a good star catalog that shows fairly faint stars; information on every star, planet, or other object that's shown (accessible by tapping the object); and even virtual tours of the planets. Its capabilities can be enhanced by a series of paid add-ons, letting you pick and choose the features you want, as opposed to apps like SkySafari 3, which offers several levels of the app for different prices. Such add-ons can quickly add up, however, and I wasn't impressed with the one (comets) I purchased.

Star Chart lacks some features, even as add-ons, that would appeal to advanced amateurs, such as telescope control. But even in its free form it's all that many beginning or casual stargazers with iPads will need to explore the night sky.

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As Analyst for printers, scanners, and projectors, Tony Hoffman tests and reviews these products and provides news coverage for these categories. Tony has worked at PC Magazine since 2004, first as a Staff Editor, then as Reviews Editor, and more recently as Managing Editor for the printers, scanners, and projectors team.
In addition to editing, Tony has written articles on digital photography and reviews of digital cameras, PCs, and iPhone apps
Prior to joining the PCMag team, Tony worked for 17 years in magazine and journal...
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